||A Content Delivery Network (CDN) is an intermediate layer of infrastructure that helps to efficiently deliver the ever increasing multimedia contents from content providers to a large community of geographically distributed clients. Content management and admission control are two essential components of the CDN architecture. In the first part of this thesis, we study content routing in large-scale CDN. A hierarchical content routing architecture is proposed, in which CDN servers perform semi-hashing based intra-cluster content routing and query-based inter-cluster content routing. In the second part of this thesis, we study object replacement algorithms for CDN servers in a CDN. We first compute and compare the hit rate of different replacement algorithms through simulation, and then develop analytical models to directly compute the hit rate of the LRU replacement algorithm. In the third part of this thesis, we study admission control in multimedia CDN. MDP tools are applied to compute and analyze the optimal admission control policy. Practical and efficient methods and algorithms are also developed to find the optimal or sub-optimal structured admission control policies, including the threshold policies and the trunk reservation policies, which are easy to implement and have very good performance when compared with the complete sharing and the global optimal admission control policies.